// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include "bits/stdc++.h"
using namespace std;
using ll = long long int;
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

/**
 * Integers modulo p, where p is a prime
 * Source: Aeren (modified from tourist?)
 *         Modmul for 64-bit mod from kactl:ModMulLL
 * Works with p < 7.2e18 with x87 80-bit long double, and p < 2^52 ~ 4.5e12 with 64-bit
 */
template<typename T>
struct Z_p{
	using Type = typename decay<decltype(T::value)>::type;
	static vector<Type> MOD_INV;
	constexpr Z_p(): value(){ }
	template<typename U> Z_p(const U &x){ value = normalize(x); }
	template<typename U> static Type normalize(const U &x){
		Type v;
		if(-mod() <= x && x < mod()) v = static_cast<Type>(x);
		else v = static_cast<Type>(x % mod());
		if(v < 0) v += mod();
		return v;
	}
	const Type& operator()() const{ return value; }
	template<typename U> explicit operator U() const{ return static_cast<U>(value); }
	constexpr static Type mod(){ return T::value; }
	Z_p &operator+=(const Z_p &otr){ if((value += otr.value) >= mod()) value -= mod(); return *this; }
	Z_p &operator-=(const Z_p &otr){ if((value -= otr.value) < 0) value += mod(); return *this; }
	template<typename U> Z_p &operator+=(const U &otr){ return *this += Z_p(otr); }
	template<typename U> Z_p &operator-=(const U &otr){ return *this -= Z_p(otr); }
	Z_p &operator++(){ return *this += 1; }
	Z_p &operator--(){ return *this -= 1; }
	Z_p operator++(int){ Z_p result(*this); *this += 1; return result; }
	Z_p operator--(int){ Z_p result(*this); *this -= 1; return result; }
	Z_p operator-() const{ return Z_p(-value); }
	template<typename U = T>
	typename enable_if<is_same<typename Z_p<U>::Type, int>::value, Z_p>::type &operator*=(const Z_p& rhs){
		#ifdef _WIN32
		uint64_t x = static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value);
		uint32_t xh = static_cast<uint32_t>(x >> 32), xl = static_cast<uint32_t>(x), d, m;
		asm(
			"divl %4; \n\t"
			: "=a" (d), "=d" (m)
			: "d" (xh), "a" (xl), "r" (mod())
		);
		value = m;
		#else
		value = normalize(static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value));
		#endif
		return *this;
	}
	template<typename U = T>
	typename enable_if<is_same<typename Z_p<U>::Type, int64_t>::value, Z_p>::type &operator*=(const Z_p &rhs){
		uint64_t ret = static_cast<uint64_t>(value) * static_cast<uint64_t>(rhs.value) - static_cast<uint64_t>(mod()) * static_cast<uint64_t>(1.L / static_cast<uint64_t>(mod()) * static_cast<uint64_t>(value) * static_cast<uint64_t>(rhs.value));
		value = normalize(static_cast<int64_t>(ret + static_cast<uint64_t>(mod()) * (ret < 0) - static_cast<uint64_t>(mod()) * (ret >= static_cast<uint64_t>(mod()))));
		return *this;
	}
	template<typename U = T>
	typename enable_if<!is_integral<typename Z_p<U>::Type>::value, Z_p>::type &operator*=(const Z_p &rhs){
		value = normalize(value * rhs.value);
		return *this;
	}
	template<typename U>
	Z_p &operator^=(U e){
		if(e < 0) *this = 1 / *this, e = -e;
		Z_p res = 1;
		for(; e; *this *= *this, e >>= 1) if(e & 1) res *= *this;
		return *this = res;
	}
	template<typename U>
	Z_p operator^(U e) const{
		return Z_p(*this) ^= e;
	}
	Z_p &operator/=(const Z_p &otr){
		Type a = otr.value, m = mod(), u = 0, v = 1;
		if(a < (int)MOD_INV.size()) return *this *= MOD_INV[a];
		while(a){
			Type t = m / a;
			m -= t * a; swap(a, m);
			u -= t * v; swap(u, v);
		}
		assert(m == 1);
		return *this *= u;
	}
	template<typename U> friend const Z_p<U> &abs(const Z_p<U> &v){ return v; }
	Type value;
};
template<typename T> bool operator==(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value == rhs.value; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> bool operator==(const Z_p<T>& lhs, U rhs){ return lhs == Z_p<T>(rhs); }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> bool operator==(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) == rhs; }
template<typename T> bool operator!=(const Z_p<T> &lhs, const Z_p<T> &rhs){ return !(lhs == rhs); }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> bool operator!=(const Z_p<T> &lhs, U rhs){ return !(lhs == rhs); }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> bool operator!=(U lhs, const Z_p<T> &rhs){ return !(lhs == rhs); }
template<typename T> bool operator<(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value < rhs.value; }
template<typename T> bool operator>(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value > rhs.value; }
template<typename T> bool operator<=(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value <= rhs.value; }
template<typename T> bool operator>=(const Z_p<T> &lhs, const Z_p<T> &rhs){ return lhs.value >= rhs.value; }
template<typename T> Z_p<T> operator+(const Z_p<T> &lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) += rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator+(const Z_p<T> &lhs, U rhs){ return Z_p<T>(lhs) += rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator+(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) += rhs; }
template<typename T> Z_p<T> operator-(const Z_p<T> &lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) -= rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator-(const Z_p<T>& lhs, U rhs){ return Z_p<T>(lhs) -= rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator-(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) -= rhs; }
template<typename T> Z_p<T> operator*(const Z_p<T> &lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) *= rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator*(const Z_p<T>& lhs, U rhs){ return Z_p<T>(lhs) *= rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator*(U lhs, const Z_p<T> &rhs){ return Z_p<T>(lhs) *= rhs; }
template<typename T> Z_p<T> operator/(const Z_p<T> &lhs, const Z_p<T> &rhs) { return Z_p<T>(lhs) /= rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator/(const Z_p<T>& lhs, U rhs) { return Z_p<T>(lhs) /= rhs; }
template<typename T, typename U, typename enable_if<is_integral<U>::value>::type* = nullptr> Z_p<T> operator/(U lhs, const Z_p<T> &rhs) { return Z_p<T>(lhs) /= rhs; }
template<typename T> istream &operator>>(istream &in, Z_p<T> &number){
	typename common_type<typename Z_p<T>::Type, int64_t>::type x;
	in >> x;
	number.value = Z_p<T>::normalize(x);
	return in;
}
template<typename T> ostream &operator<<(ostream &out, const Z_p<T> &number){ return out << number(); }

/*
using ModType = int;
struct VarMod{ static ModType value; };
ModType VarMod::value;
ModType &mod = VarMod::value;
using Zp = Z_p<VarMod>;
*/

// constexpr int mod = 1e9 + 7; // 1000000007
constexpr int mod = (119 << 23) + 1; // 998244353
// constexpr int mod = 1e9 + 9; // 1000000009
using Zp = Z_p<integral_constant<decay<decltype(mod)>::type, mod>>;

template<typename T> vector<typename Z_p<T>::Type> Z_p<T>::MOD_INV;
template<typename T = integral_constant<decay<decltype(mod)>::type, mod>>
void precalc_inverse(int SZ){
	auto &inv = Z_p<T>::MOD_INV;
	if(inv.empty()) inv.assign(2, 1);
	for(; inv.size() <= SZ; ) inv.push_back((mod - 1LL * mod / (int)inv.size() * inv[mod % (int)inv.size()]) % mod);
}

template<typename T>
vector<T> precalc_power(T base, int SZ){
	vector<T> res(SZ + 1, 1);
	for(auto i = 1; i <= SZ; ++ i) res[i] = res[i - 1] * base;
	return res;
}

template<typename T>
vector<T> precalc_factorial(int SZ){
	vector<T> res(SZ + 1, 1); res[0] = 1;
	for(auto i = 1; i <= SZ; ++ i) res[i] = res[i - 1] * i;
	return res;
}

int main()
{
    ios::sync_with_stdio(false); cin.tie(0);

    auto fac = precalc_factorial<Zp>(600005);
    auto C = [&] (int n, int r) {
        if (r < 0 or n < r) return Zp(0);
        return fac[n] / (fac[r] * fac[n-r]);
    };

    int x, y, z, w; cin >> x >> y >> z >> w;
    Zp ans = 0;
    if (z == 0) {
        // All humans gone -> last is a human
        // a1 + a2 + ... + ax = y - w, all are >= 0
        cout << fac[x] * C(y, w) * fac[y-w] * C(y-w + x - 1, x - 1) << '\n';
    }
    else {
        cout << fac[y] * C(x, z) * fac[x-z] * C(x-z + y-1, y-1) << '\n';
    }
    // cout << ans << '\n';
}